With continuous profile of the manufacture of forming materials and material combinations passing the material a tool that defines the profile cross-section at the extrusion pressure through the material, in pultrusion drawn through it. The result is profiles that have the same cross-section all the way.
Often, to various applications have beams and profiles with patterns, cogs, varied thickness, anti-slip design, logo, etc. This integrated as a profile that has the same cross-section or the look all the way often does not meet the requirements to be able to satisfy customers' requirements and applications Design, Function and performance in sectors such as construction, consumer products, structural applications, transportation, aerospace, automotive and design.
The traditional methods only produce profiles and then process the varied thickness or patterns usually require significant costs for processing and processing equipment.
An alternative method for the first extruded and then process the profile is the use of rotating patterned arrays at the extrusion, leaving a “negative imprint” of the profile, while its cross section is defined.
This has been described in technical papers (ex. way “How to Extrusion embossed flexible profiles” of Pierre Hamel in Plastics Engineering strip 36, No. 6, June 1980 pp. 34-35), which describes how to use the rotary dies (engraving wheel see FIG. 1) when patterning extruded plastic profiles.
Another method to produce profiles with the pattern described in the patent EP 1272330 B1 of the innovator D. Czekay which uses a “caterpillar track” as shaping member, whose relief disparate stamping patterns are moving in approximately the same speed as the extruded profile.
Another patent that describes extrusion with rotating arrays are SE504300 (C2), which describes how to extruded ladder-similar profiles. However, it is not possible to proceed in accordance with the described patent, for example if you shall extrude materials which require high pressure to achieve sufficient plasticity, the forces on the rotating shaping member/organ would be so large due the big exposed area that it would bend and the bearings would break down. At the extrusion of aluminium, copper, magnesium, titanium, metal composites etc. the pressure can involve several thousand pounds pressure per square centimetre, which precludes the procedure described in SE 504300 (C2). This is due to forces as well as material flow conditions.
The patent SE514815 (C2) displayed a more realistic performance of extrusion using so-called rotary dies; however, this patent is very similar to Pierre Hamel's Technical Paper of 1980.
Both patent SE504300 (C2) and patent SE514815 (C2) can be said to describe the approach of extrusion dies with rotating dies according to Pierre Hamel instructions from 1980.
SE514815 (C2), however, is in fact strongly limited in their opportunities in the thin extruded profiles, advanced cross-sections with varied thickness and varied depth, great depth of pattern, hollow sections, weak profiles and asymmetric profiles due to the problems with adhesion between the thin weak profile wall and the rotating die member due to adhesion and interference adhesion between the rotating members surface and the extruded material.
Another factor that hampers performance under SE514815 (C2) is the friction difference see FIG. 4, which is inevitable between the rotary bearing surfaces (10) and static bearing surfaces (22), as in the cases when elimination of adhesion between the out-going profile (12) and rotating bearing (10) is achieved, resulting in the greater friction in the static bearing surface brakes outgoing material speed and cause a “local imbalance in the flow” resulting in deviation away from rotating die.
The same applies when extruding profiles with great imprint-depth relative to wall-thickness, see FIGS. 2 & 3, the profile often tend to “follow with” a rotating member at start-up and billet-changes, resulting in very high risk of process-breakdown and tools-breakdown, when the outgoing material locks the rotating member or get stuck on the way out of the die.
Problems with the start-up have made it practically impossible to industrialise the production profile extrusion with rotating dies. This as a result of that market do not ask for the simple, solid, thick and mainly symmetric profiles with relatively shallow pattern without thickness variation, that has been possible to produce.
The present invention makes it possible to make stable starts of extrusion process, in other words, the prospect of industrial, manufacturing of commercially viable products/profiles, which opens for the industrialization of the production of profiles with rotating dies, both through increased process stability and significantly increase in the degree of freedom, which is made possible.
Earlier, attempts have been made with rotating dies to get some variations, however, this has been problematic for purposes of the weak, thin profiles or hollow sections, or profiles with advanced cross-section, above all because of problems at start up due to adhesion between the rotating die and extruded material as well as flow imbalance.
The application of the present invention is applicable to all types of pultrusion and extrusion lines, with minimal or no adaptation needs of the facility, including hydraulic presses for metal extrusion, screw extruders for rubber/plastic, conform extrusion machines and pultrusion lines.